1. Field of the Invention
The present invention relates to a liquid container detachably mounted on an ink jet recording apparatus, and a recording apparatus utilizing such liquid container.
2. Related Background Art
The liquid container mounted on an ink jet recording apparatus, for executing recording by discharging liquid droplet onto a recording sheet, is generally classified into two types, namely a type detachably mounted in the recording apparatus but used in a fixed state, and a type used in a moving state together with a recording head in the transversal direction of the recording sheet in a recording apparatus of so-called serial scan type. The serial scanning means a system in which the recording head is moved in a direction crossing the conveying direction of the recording sheet.
In the so-called on-demand ink jet recording which is a currently prevailing system among various ink jet recording methods and forms a recorded image by discharging a liquid droplet onto a sheet (such as paper) in response to a recording signal, it is essential to maintain a somewhat negative pressure relative to the atmospheric pressure at the nozzle end (also called orifice) of the recording head, in order to discharge the liquid droplet always in a stable manner in response to the recording signal.
The liquid container of the latter type moving together with the recording head of serial scan type is also called an on-carriage tank and is employed widely, because the recording head and the liquid container, containing liquid to be supplied to the recording head, are positioned close whereby the ink supply path can be made shorter and the recording apparatus can be realized compact.
Also as a configuration capable of retaining the liquid therein and supplying the liquid to the exterior, there is commonly used a liquid container utilizing a foamed member such as urethane foam or an entangled fibrous member such as of polypropylene fibers as a capillary force generating member.
However, in case of the latter on-carriage tank, the liquid container mountable together with the recording head on the carriage has a certain limitation in size. More specifically, if a large liquid container is employed in order to reduce the frequency of replacement of the liquid container, there is required an enormous space in order not to hinder the movement of such liquid container, so that the recording apparatus itself becomes large. This drawback becomes more serious in a 4-color or 6-color recording apparatus.
In consideration of such fact, there is increasingly employed the recording apparatus having the ink tank in detachable manner in a fixed position in the apparatus instead of mounting the ink tank on the carriage supporting the recording head, particularly in case of a wide format printer utilizing a very wide recording sheet (liquid supply amount per sheet being accordingly large) or a network printer which is a recording apparatus of a very high working rate. The liquid container in such recording apparatus corresponds to the former and, particularly in case of the recording apparatus of serial scan type, is called an out-carriage tank or an off-carriage tank because the liquid container is fixed in the recording apparatus independently from the movable carriage.
However, such conventional liquid containers have been associated with drawbacks to resolve. Such issues will be explained in the following by the examples of the prior art.
FIG. 22 shows a liquid container 101 having two fluid connection ports 102, 103 with the exterior, approximately at the center of an upper face 101a of the liquid container. The connection port 102 is exclusively for deriving liquid 105 from the upper face 101a through an internal supply pipe 104 so provided as to reach the bottom 101b, in order to securely extract the liquid while the liquid level is lowered by the liquid extraction, until the container becomes almost empty. The other connection port 103 is exclusively for opening to the external air and is so constructed as to directly communicate with the air present above the liquid level in the container.
In such liquid container 101, the liquid level open to the air therefore varies from the upper part 101a of the container to the bottom 101b thereof. Consequently such liquid container, if directly connected to the ink jet recording head, shows a wide range in the supplied negative pressure, so that the liquid container cannot be made very large (particularly in the direction of gravity).
Also, if there is employed a supply system which once transfers the liquid from the liquid container to the exterior and stabilizes the negative pressure by a relaying tank, there will be required additional components such as a transfer pump and a relaying tank. Furthermore, the connection pipe 103 open to the air is not in contact with the contained liquid 105 in the liquid container and cannot therefore be used as a conductive electrode for detecting the remaining ink amount in combination with the other connection pipe 102, so that there is required another method such as forming a hole in the container bottom 101b and inserting an electrode for detecting the remaining amount of the contained liquid. Such method inevitably leads to additional drawbacks of an increase in the cost and possible liquid leakage.
FIG. 23 shows a liquid container 201 of lateral mounting type, in which a connection port 202 for liquid extraction is formed on a lateral face close to the bottom 201b of the liquid container 201 and a connection port for opening to the air is formed on a lateral face close to the upper part 201a of the liquid container 201. Such liquid container does not require the internal supply pipe but other drawbacks are same as those of the liquid container shown in FIG. 22.
In the ink jet recording technology, there are being required clarity, water resistance, light fastness etc. of the print, and it is proposed to use pigment as the coloring agent of the ink as one of the methods for meeting such requirements. In the pigment-based ink, the pigment is dispersed in ink solvent, and the pigment, having a specific gravity larger than that of the solvent, tends to precipitate after a prolonged standing. For this reason, the pigment concentration becomes different between the upper part and the lower part of the ink contained in the ink tank, thereby generating fluctuation in the print density.
An ink tank disclosed in the Japanese Patent Applications Laid-open Nos. 9-164698, 11-348308 etc. is provided, on the bottom of the container, with a connection port which is positioned close to a lateral wall of the container, but such arrangement of the connection port is determined by the position of an ink supplying pump and does not provide any solution to the pigment precipitation in case pigment is used in the ink.
Also an ink tank disclosed in the Japanese Patent No. 2,929,804 is provided at the bottom thereof with a connection port into which a connection needle communicating with the air and a connection needle for liquid derivation are to be inserted and which is positioned at the center of the tank. Such container configuration is not suitable for a replaceable container since a strong force is required at the connecting operation and the inserting positions of the needles cannot be fixed at each insertion. However there are not taught the issue of pigment precipitation and the position for ink extraction.
Also an ink tank disclosed in the Japanese Patent Application Laid-open No. 10-337879 and the U.S. Pat. No. 6,074,042 has a complex configuration in which an ink chamber is composed of a flexible bag that can be flattened in order to use up the ink contained therein and such flexible bag is pressurized in a casing. Consequently the ink containing space is generally small within the ink tank casing and such configuration is difficult to use for the purpose of providing a tank of a high containing efficiency within a limited space.
Also an ink tank disclosed in the Japanese Patent Application Laid-open No. 10-286972 (cf. FIGS. 1, 6, 7 etc. therein) is provided on the bottom thereof with plural joint points each of which is a free joint composed of an elastic seal member impinging on a substantially flat portion of the tank bottom and an ink supply pipe (with a filter on top) contacting a capillary member contained in the tank for retaining ink therein, wherein an ink supply pipe is positioned at the center of the elastic member. There is thus disclosed a joint portion for an independent ink chamber.
Also an ink tank disclosed in the Japanese Patent Application Laid-open No. 10-95129 (cf. FIG. 6 therein) is provided with plural joint portions for an ink chamber, and such plural joint portions are all for ink derivation. Also the joint portion is composed of an ink absorbent member.
Also an ink tank disclosed in the Japanese Patent Application Laid-open No. 8-132635 (cf. FIGS. 1 and 7 therein) is also provided on the tank bottom with plural joint portions, each of which is so constructed that a plastic ink supply pipe (having a small hole in the tapered portion) penetrates and is pinched by an elastic seal member provided in a port on the tank bottom. Also a portion where the elastic seal member is provided constitutes a small ink chamber directly containing ink, above which provided, across a filter, is a chamber containing a capillary member for retaining ink. Thus, there is disclosed a joint portion for an independent small ink chamber.
Also an ink tank disclosed in the Japanese Patent Publication Nos. 2000-218817 (cf. FIG. 7 therein) and 2000-218824 (cf. FIGS. 6 and 22 therein) is provided with a memory medium for memorizing the tank interior information, but such memory medium is provided on a lateral face of the tank and is fixed in position.
An ink tank disclosed in the Japanese Patent Application Laid-open No. 9-85962 (cf. FIG. 1 therein) is provided in the lower part of the tank with two connection ports for air introduction and for liquid derivation, but there is not taught the issue of pigment precipitation in case of using pigment in the ink. The illustrated tank has two connection ports respectively on both ends, but there is not mentioned the positional relationship of the connection port for liquid derivation and that for air introduction.
On the other hand, in a tank having the connection port downwards, the elastic member employed for sealing the connection port is always in contact with the ink and is therefore not only susceptible to deterioration by the ink but also has to achieve the closing action by wiping off the needle with the elastic member so as to cut off the ink. Particularly in case of employing a needle of a diameter of 1.5 mm or larger in order to improve the ink supplying ability, ink dripping may result before the elastic member completes the sealing action even with the commonly adopted ink properties (specific gravity 1 to 2.2, viscosity 2 to 4 cp, surface tension 25 to 50 mPaxc2x7s).
Also in a configuration of detecting the presence or absence of remaining ink by providing the tank bottom with two independent conductive connection needles and applying a voltage therebetween, though the casing need not be newly provided with a penetrating portion for the electrode, ink dripping may still result because two needles are constantly immersed in the ink until the ink tank becomes empty and also because one of the needles communicates with the external air.
In addition, in the ink jet recording, there is being introduced pigment-based ink superior in water resistance and color development in comparison with the dye-based ink as explained in the foregoing, and there is also used ink containing fine resinous particles in order to improve fixation to the recording sheet.
In the aforementioned conventional off-carriage ink tank system, since the ink tank is fixed in position even during the recording operation and the pigment or fine resinous particles contained in the ink are insoluble in solvent water, such pigment or fine resinous particles precipitate to the tank bottom with the lapse of time under the influence of gravity. Such precipitation of pigment or fine resinous particles results in a difference in concentration between the upper part and the lower part of the ink tank, thereby affecting the density or fixability of the formed record or eventually leading to the clogging of the nozzles of the recording head, resulting from the supply of concentrated ink thereto.
For avoiding such drawbacks, it is conceivable to provide the ink tank with an agitating mechanism for forcedly agitating the ink in the ink tank. However, it is not desirable to add an agitating mechanism to the ink tank since the ink tank is so-called consumable to be replaced by a new one when the ink contained in the ink tank is depleted.
In the foregoing, there have been explained the drawbacks of the prior technologies by taking ink tanks as examples, but the aforementioned drawbacks resulting from precipitation may occur not only in the ink tank but also in a liquid container which contains liquid containing an insoluble substance in a dispersed state and is required to supply such liquid to the exterior without causing concentration change therein.
In consideration of the foregoing, an object of the present invention is to provide a novel liquid container provided with a connection port at the bottom and with, inside the connection port, a common chamber directly containing ink without employing a capillary member for ink retaining, capable of stably supplying the ink to the exterior until the container is almost depleted and also capable of achieving simple detection of remaining ink amount and resolving the uneven distribution of the ink component in standing over a prolonged period.
Another object of the present invention is to provide a liquid container and a liquid supply system capable of supplying liquid to the exterior with a stable concentration by a simple structure, and a method of agitating the liquid in such liquid container. Still another object of the present invention is to provide an ink jet recording apparatus capable of supplying the recording head with ink of stable concentration, thereby achieving recording of high quality.
The above-mentioned objects can be attained, according to an embodiment of the present invention, by a liquid container to be detachably mounted on a vertically upward port, having a flat shape and Phi provided at the bottom with two independent fluid connection ports for communicating the liquid chamber with the exterior of the container wherein the two connection ports are provided close to an end of the bottom.
In the above-mentioned liquid container, the external shape and the internal space thereof are preferably pointed toward the bottom of the container.
Also, the aforementioned two fluid connection ports are preferably positioned on a line passing through the approximate center of the shorter side of the flat shape of the liquid container.
Also, the fluid connection port closer to the end of the bottom of the liquid container is preferably used for allowing derivation of the liquid in the liquid chamber. As the liquid is derived from such fluid connection port, the liquid itself flows in the liquid chamber whereby the pigment can be diffused and homogenized in case the pigment is used as a component of the contained liquid. In the fluid connection port closer to the end of the bottom of the liquid container of flat shape, the nearby space is surrounded by three walls directed to the ceiling of the container, the liquid in the vicinity is moved and is easily agitated even with a low derivation amount of the liquid.
Also there is preferably provided a member for filtering the derived liquid, so as to cover the fluid connection port closer to the aforementioned end.
Also the fluid connection port closer to the center of the bottom of the liquid container is preferably used for allowing air introduction. In case the contained liquid employs the pigment as a component thereof, since the internal space (liquid chamber) of the container is pointed toward the bottom and the fluid connection port is provided closer to the center of the bottom of the container, when air is introduced in an amount matching the derived amount of the contained liquid, bubbles float at the approximate center, where the pigment tends to be concentrated, in the pigment precipitation area at the bottom of the liquid chamber thereby agitating the contained liquid to achieve diffusion and homogenization thereof.
Also, a tubular member is preferably provided protruding toward the ceiling part of the liquid chamber so as to surround the aforementioned fluid connection port closer to the center of the liquid chamber. The lateral face of such tubular member serves as a wall to the fluid connection port closer to the end of the bottom of the liquid container of flat shape, the bubbles from the fluid connection port closer to the center do not easily move to the fluid connection port closer to the end, and, in case of liquid derivation from the aforementioned fluid connection port closer to the end, the contained liquid is moved and is agitated more easily even at a low liquid derivation amount, in comparison with a case where the tubular member is absent. Also in the presence of such tubular member, by forming two connection needles, to be respectively connected to the two fluid connection ports on the bottom of the container, with a conductive material and maintaining the connected needles at a position lower than the upper end of the tubular member, it is rendered possible to easily judge the remaining amount of the contained liquid by the conductive state between the connection needles.
Also, by providing a structure disturbing the rising movement of the bubbles in an upper space in which the air bubbles rise from the bottom portion of the tubular member along with the liquid derivation, it is rendered possible suppress and recover the uneven distribution or precipitation of the pigment or specified component. Also, such structure may serve also as a rib, which connects the two opposed faces of largest area of the liquid container of flat shape and prevents crushing or inflation of the liquid container.
Also the aforementioned two fluid connection ports are preferably provided with elastic members for sealing the liquid chamber.
Also there is preferably provided an identification information structure for mechanically memorizing the identification information of the liquid container, in such a manner as to substantially perpendicularly protrude from a face continued to and crossing the longitudinal end of the oblong bottom of the liquid container. In this manner, in case of using several liquid containers containing different liquids as a set in a liquid supply system or a recording apparatus, it is rendered possible to securely prevent erroneous mounting, in the specified mounting position of each liquid container, of a wrong liquid container.
Also, in an area of the bottom of the liquid container where the fluid connection ports are not provided, there is preferably provided an information memory element based on an electric, magnetic, optical or combined system and capable of holding identification information for the liquid container.
Such information memory element is preferably capable, in addition to readout of the memorized information from the exterior of the liquid container, of alteration, deletion or additional writing of the memorized information.
According to another embodiment of the present invention, there is provided a liquid supply system employing the aforementioned liquid container, wherein an air introducing connection needle and a liquid deriving connection needle are respectively connected to the two connection ports in the bottom of the liquid container.
According to still another embodiment of the present invention, there is provided a liquid supply system employing the aforementioned liquid container, wherein the system is provided with an air introducing connection needle and a liquid deriving connection needle to be respectively connected to the two connection ports in the bottom of the liquid container, the air introducing connection needle is so positioned as to remain within the aforementioned tubular member and the liquid deriving connection needle is provided at a height approximately same as that of the air introducing connection needle.
Also, in the liquid supply system of these embodiments, there is preferably provided a liquid discharge head which is connected, through a liquid supply tube, to an end of the liquid deriving connection needle opposite to the connection end thereof to the liquid container. Such liquid discharge head is preferably an ink jet head for causing a liquid droplet to fly by pushing out the liquid in a nozzle by thermal or vibration energy.
According to still another embodiment, there is provided an ink jet recording apparatus on which the aforementioned liquid container is detachably mountable.
There is furthermore provided a method of mounting on an ink jet recording apparatus comprising:
a step of guiding the liquid container principally utilizing the external shape portion in the projection plane in the inserting direction until the front end portion of a connection member of the recording apparatus enters a connection member introduction guide member of the liquid container, which enables smooth connection to the two fluid connection ports in the bottom of the liquid container;
a step of relaxing the positional defining by the aforementioned external shape portion after the front end portion of the connection member enters the guide portion of the fluid connection port in the bottom of the liquid container;
a succeeding step of executing entry of the connection member into the fluid connection port; and
a succeeding step of starting the connection of a connector corresponding to an information memory element with the information memory element.
Furthermore, the aforementioned objects can be attained, according to the present invention, by a liquid container comprising:
a liquid chamber containing liquid;
a liquid supply portion provided in the bottom portion of the liquid chamber for supplying the liquid in the liquid chamber to the exterior;
an air introducing portion provided in the bottom portion of the liquid chamber and adapted to introduce air into the liquid chamber so as to maintain a constant pressure in the liquid chamber along with the liquid supply by the liquid supply portion; and
a liquid agitating structure provided inside the liquid chamber and adapted to agitate the liquid in the liquid chamber, utilizing liquid flow generated in the liquid chamber by the air introduction from the air introducing portion into the liquid chamber.
As the liquid agitating structure, there can be utilized at least a rib structured member provided protruding from the internal wall of the liquid chamber.
In the liquid container of the present invention, when air is introduced from the air introducing portion into the liquid chamber, the introduced air rises as bubbles in the liquid. The movement of the bubbles generates a liquid flow in the liquid chamber, in the vicinity of the air introducing portion. Such flow collides with the liquid agitating structure and is thus disturbed, whereby the agitation of the liquid in the liquid chamber is accelerated to achieve supply of the liquid of a stable concentration from the liquid supply portion to the exterior.
The liquid agitating structure can be realized by an extremely simple structure such as a rib protruding from the internal wall of the liquid chamber. In order to effectively agitate the liquid flow, the rib is preferably provided higher than the air introducing portion. Also by forming the rib between the air introducing portion and the liquid supply portion, the liquid to be agitated in the vicinity of the air introducing portion is prevented from gathering in the vicinity of the liquid supply portion. Also by forming ribs on mutually opposed positions on the mutually opposed two internal walls of the liquid chamber, the liquid flows respectively directed to the lateral walls and deflected by the ribs mutually collide to further stimulate the liquid agitation.
In case it is difficult to direct the liquid flow in the liquid chamber to the lateral wall, the rib may be formed as a pillar-shaped member connecting the mutually opposed two internal wall of the liquid chamber. In such case, the pillar-shaped member may be provided in a position to be collided by the rising liquid flow generated in the liquid chamber or in a position above the air introducing portion and between the liquid supply portion and the air introducing portion, thereby achieving more efficient liquid agitation.
Also the liquid supply system of the present invention comprises:
an aforementioned liquid container of the present invention;
liquid supply means connected with the liquid supply portion of the liquid container for supplying the liquid in the liquid chamber to the exterior of the liquid chamber; and
air introducing means connected with the air introducing portion of the liquid container thereby causing the interior of the liquid chamber to communicate with the air.
Presence of the aforementioned liquid supply means and air introducing means allows effective exploitation of the functions of the aforementioned liquid container of the present invention, thereby enabling supply of the liquid of stabilized concentration to the exterior.
Also the ink jet recording apparatus of the present invention is an ink jet recording apparatus for recording on a recording medium by discharging liquid ink, comprising:
holding means for detachably holding a recording head for executing recording by discharging ink;
the aforementioned liquid container of the present invention for containing ink to be supplied to the recording head;
a liquid supply unit for connecting the recording head and the aforementioned liquid supply portion of the liquid container thereby supplying ink in the aforementioned liquid chamber to the recording head along with the ink discharge from the recording head and communicating the interior of the liquid chamber with the air through the aforementioned air introducing portion of the liquid container; and
suction for forcedly sucking the ink in the recording head.
In the ink jet recording apparatus of the present invention, prior to the recording by the recording head, the suction means forcedly sucks the ink in the recording head thereby sucking the ink in the liquid container through the liquid supply system, whereby the ink in the liquid container is agitated as described in the foregoing. In this manner ink of stable concentration is used for recording, thereby enabling formation of a satisfactory image with stable density.
The liquid agitating method of the present invention is to agitate the liquid in a liquid container comprising a liquid chamber containing liquid; a liquid supply portion provided in the bottom portion of the liquid chamber for supplying the liquid in the liquid chamber to the exterior; an air introducing portion provided in the bottom portion of the liquid chamber and adapted to introduce air into the liquid chamber; and a rib provided on the internal wall of the liquid chamber, the method comprising:
a step of supplying the liquid in the liquid chamber from the liquid supply portion to the exterior; and
a step of introducing air from the air introducing portion into the liquid chamber so as to maintain constant the pressure in the liquid chamber, decreasing by the liquid supply from the liquid supply portion to the exterior, and generating a flow in the liquid in the liquid chamber directed directly or indirectly toward the rib.
By introducing air into the liquid chamber along with the supply of the liquid from the liquid chamber to the exterior thereby generating a liquid flow toward the rib in the liquid chamber, the flow generated in the liquid chamber is disturbed by the rib whereby the liquid in the liquid chamber is effectively agitated.
In the present invention, words upper, lower and bottom used for indicating the position or direction means upper, lower and bottom of the container in the state of use thereof.